Aspects of this disclosure relate generally to telecommunications, and more particularly to uplink scheduling.
Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
A long-term evolution (LTE) wireless communication network may include a number of eNodeBs that can support communication for a number of user equipments (UEs). A UE may communicate with an eNodeB via the downlink and uplink. The downlink (or forward link) refers to the communication link from the eNodeB to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the eNodeB.
Operation of wireless devices in certain portions of a shared or unlicensed spectrum may experience interference from another radio access technology (RAT) using the spectrum. For example, both LTE and Wi-Fi may operate in an unlicensed 5 GHz band. Over-the-air interference detection is employed in some wireless communication networks in an attempt to mitigate such interference. For example, a device may periodically monitor (e.g., sniff) for energy in the RF band used by the device. Upon detection of any kind of energy, the device may back-off the RF band for a period of time. Such process may be referred to as clear channel assessment (CCA).
In practice, however, there may be problems with such a back-off or “listen-before-talk” (LBT) approach, at least when applied to radio technologies using a frame structure and uplink grants. For example, for an LTE system operating in an unlicensed or shared band, a UE may need to consider both uplink grants scheduled by the eNodeB and LBT or CCA requirements. In view of the foregoing, it may be understood that there may be significant problems and shortcomings associated with operation of wireless devices in shared and unlicensed spectrum.